This invention relates to a vaporizer for converting propane in its liquid phase to propane under pressure in its gaseous phase. The invention is equally applicable to converting any other compound, mixture or element from liquid to gaseous phase where the material can be maintained in liquid phase under pressure and is normally in a gaseous phase at pressures near atmospheric.
Vaporizers capable of processing in the neighborhood of from 100 to 600 gallons per hour of liquid propane into gaseous propane are often employed as primary gas generator units or as standby units to supplement or temporarily replace supplies of gas from pipe lines. Such vaporizers must sometimes stand idle for extended periods; but must be highly reliable to supply gas without failure or interruption on very short notice.
Before the present invention, units designed to fulfill similar requirements have tended to be unreliable. Factors contributing to unreliability included the necessity or desirability of installing such vaporizers outside or, if inside, at locations where moisture is present in the ambient air. Because of this, condensation often resulted from temperature changes occurring from alternate operation and shut-down of the vaporizer and from changes in weather conditions, and so rusting and other corrosion was present.
Controls often kept in damp and cold (sometimes freezing) environments and necessarily operated without opportunity for warming and/or drying often malfunctioned or broke down.
The relatively cold temperature of the pipe carrying liquid propane to the vaporizer tends to cause condensation of any and all moisture coming in contact with it and this condensation drops from such pipe to have a rusting or other corrosive effect on the areas it contacts unless provisions are made to evaporate it and drive it off.
Specifically, temperature sensors, electronic controls, electronic and fluid control conduits, and control boxes in which they have been installed have rapidly deteriorated due to the attack of moisture thereon.
Within the heat exchange portion of the vaporizer itself, a problem has been the stratification into thermal layers of the water or other heat transfer liquid. The introduction of cold liquid propane into a heat transfer pipe in such a manner as to cause circulation of the water within the heat exchanger and to prevent stratification of the heat in the water would maximize the heat transfer effect.
Also, the flow of liquid propane into the heat transfer pipe in a heat transfer medium, the flow of propane through the heat transfer pipe and the flow of gaseous propane out of this pipe after vaporization has taken place, at flow rates of more than 100 gallons (378.5 liters) of liquid per hour to less than 600 gallons (2.271 kiloliters) per hour, tends to be a laminar flow. This is not as favorable for efficient heat transfer as would be a turbulent flow. The supply of cold liquid propane in such a manner as to cause greatest turbulence of the propane as it proceeds through the coil would further maximize the heat transfer effect.
The providing of the maximum area of contact between the flues carrying the products of combustion and heated air and the heat transfer liquid in the water bath without inhibiting the draft effect of the vertical upward passage of these combustion products would also tend to maximize the heat transfer.
No search of the prior art was made before the preparation and filing of this patent application. However, applicants are not aware of any prior art that anticipates the claims made herein.